Since each set of lights is on a different circuit, i.e.; left/right park lights, left low beam/right low beam, etc., the common element is the headlight switch.

That's what I'd be focusing on.

Jim

__________________
14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles